It is well known that the seat pocket in a valve body wears away as the valve is used. There are several factors that cause this wearing away; such as, friction between the valve seating core and the seat pocket when the valve is opened anc closed, the flow of the fluid around the seat pocket and the corrosive nature of the fluid passing through the valve. As the seat pocket wears away, the seal between the seating core and the seat pocket becomes less efficient. Eventually, the valve must be replaced with a new valve or the old valve is rebuilt. The latter case is extremely desirable in large valves because of the cost in replacing such valves.
One method of rebuilding these valves has been by appropriate machining of the seat pocket to add a bushing for providing a new seat. This method, however, is extremely expensive and quite frequently the bushings wash out.
Another method is to add material to the seat pocket, as by welding, and then machining the welded area to the proper shape for sealing engagement with the seating core. This method has the advantage in that no bushings are available which may be washed out. However, in many situations the labor expense to weld the valve bodies has become prohibitive.
Accordingly, it is the primary aim of the present invention to provide apparatus used in the rebuilding of the body of a valve that will quickly and easily add material to a valve body after which the valve may be properly machined.
In accordance with the invention, the body of a valve is rebuilt by using electrical welding means, first support means, second support means and driving means. The electrical welding means add material inside the valve body by using an electrode to provide an arc. The first support means detachably supports the valve body by aligning the valve body with a hole. The second support means rotatably supports the electrode of the welding means in a relatively fixed relationship to the valve body and has an elongate tubular member extending through the hole in the first support means. The driving means rotates the tubular member and electrode about the elongate axis of the tubular member for adding the material to a desired location on the valve body.